dhcpdbyport is
a perl script which generates configurations files for ISC DHCP v3
and (cisco) switches.

The goal is to
assigned a fixed ip address, not based on mac addresse as usual, but
on the equipement (switch?) port used to connect to the network using
DHCP Option-82.This is usefull when you have user/port or
customers/port associations, like in hotel, dormytory, residential
area.

Currently,
dhcpdbyport also generate the port configuration part of a cisco
switch, to enforce that only the assigned ip adress can be used as
source address, using layer 3 ACL on layer 2 switch ports (available
on EI cisco switches starting from 2950T, 2950G)